Should i take 7850 iceQ and overclocked it
gtx 660, but overclock it about 5% from stock speed
I'm not bought any GPU cooler
Like others have said, you can't count on overclocking potential. You would need a good overclock out of the 7850 for it to consistently beat the 660. At those prices, I would take option 3 and overclock it 5-10% if you can. You'll be very happy with it.